Amyotrophic Lateral Sclerosis (ALS) is an adult-onset, devastating, neurodegenerative disease characterized by the loss of cortical, brain stem, and spinal motor neurons. Visual evoked potentials studies in patients with ALS suggest visual pathway involvement. Optic coherence tomography (OCT) is a non-invasive cross-sectional imaging modality measuring the optical reflections in biological tissues. The main objective of this observational cohort study is to explore the correlation between changes on OCT retinal parameters and and clinical disability as measured by the ALS Functional Rating Scale (ALS-FRS-r) in patients with ALS at baseline, 3 and 6 months. A secondary objective is to explore the correlation between changes in retinal OCT parameters and pulmonary function tests (FVC and FEV1) in this cohort of patients with ALS. A parallel cohort of healthy age and sex matched subjects will participate as controls to obtain reference values of their retinal layers' thickness at baseline, 3 and 6 months.

Inclusion Criteria:

• Diagnosis of ALS according to the El Escorial criteria.
• Age 18 years to 80 years old
• Disease duration less than 36 months
• Patients logistically able to attend and be evaluated at baseline, 3 and 6 months

Exclusion Criteria:

• Patients with diabetes mellitus
• Patients with glaucoma, refractive errors of ± 6 diopters or more, or other ophthalmologic disorders such as media opacities that could interfere with retinal OCT assessment